If I'm halfway through a barrel roll on final descent, on an ILS, will I get reverse sensing on my glide slope indicator?
Well first off said stunt is illegal under 91.303 aerobatic flight regs and 91.13 careless and reckless operation of an aircraft. And it's also very dangerous. But no, it would not result in reverse sensing due to the fact that the ILS system is only capable of sensing whether it is receiving more of the 90 Hz signal as opposed to the 150 Hz signal and interprets this as either above or below glideslope. It cannot differentiate between erect and inverted flight.